Dual-flow-baffle compound gasoline fractionator of ethylene unit

ABSTRACT

The invention discloses a dual-flaw-baffle compound gasoline fractionator of ethylene unit, a quench oil circulation section is provided with micro baffles which are arranged in parallel in the vertical direction at intervals, a vertex angle of the micro baffle ranges from 90 to 139 degrees, symmetrical bevel edges at two sides of the vertex angle of the micro baffle are provided with symmetrical vertical hems, a medium oil circulation section is provided with dual-flow trays which are arranged in the vertical direction and have meshes with the diameter ranging from Φ18 to 24 mm, a diesel oil separation section is provided with dual-flow trays which are arranged in the vertical direction and have meshes with the diameter ranging from Φ13 to 24 mm, and a gasoline separation section is provided with dual-flow trays which are arranged in the vertical direction and have meshes with the diameter ranging from Φ13 to 18 mm. The gasoline fractionator overcomes the frequent problem of polymer plugging in current plate-type fractionator, and has the prominent advantages of strong impact vibration resistance, reduced pressure of entire tower, high ethylene yield, outstanding energy-saving effect and being capable of ensuring long-term stable operation of this tower.

REFERENCE TO PENDING APPLICATIONS

This application claims the benefit of International Application No.PCT/CN2011/070724 filed Feb. 17, 2011.

BACKGROUND OF THE INVENTION

The invention belongs to chemical separation equipment, and moreparticularly to a dual-flaw-baffle compound gasoline fractionator ofethylene unit.

Being leading equipment of ethylene unit, gasoline fractionator hasbecome a symbolic embodiment of the level of chemical separationtechnology,

The current plate-type gasoline fractionator consists of a quench oilcirculation section, a medium oil circulation section, a diesel oilseparation section and a gasoline separation section, the quench oilcirculation section is composed of nozzle-type liquid distributors,three-dimensional compound guide-type inlet initial distributors and alarge-scale baffle or an angle steel tower tray or a medium-mesh rippledual-flow tray (Φ12 mm, similarly hereinafter), the medium oilcirculation section is composed of nozzle-type liquid distributors,high-circulation oil collecting tanks and a fixed valve tower tray or anangle steel tower tray or a medium-mesh ripple dual-flow tray, thediesel oil separation section is composed of a fixed valve tower tray ora medium-mesh ripple dual-flow tray, and the gasoline separation sectionis composed of nozzle-type liquid distributors and a fixed valve towertray or a medium-mesh ripple dual-now tray.

At present, the plate-type gasoline fractionator is impacted by thefollowing major problems throughout the world: as the diesel oilseparation section is just positioned in a polymerization zone, pluggingof liquid distributor or tower tray caused by polymers occurs quiteoften; and plugging of heat exchanger, liquid distributor or tower trayis often caused by coking matters resulted from cracking on {he quenchoil circulation section.

In order to avoid the plugging described above to further advantagelong-term operation, technological measures such as the addition ofpolymerization inhibitor, antioxidant and the like are adopteddomestically and overseas in most cases, achieving great efficiency butcosting tremendous expenditure, furthermore, many domestic pluggingaccident still occurs.

SUMMARY OF INVENTION

The invention aims at disclosing a dual-flow-baffle compound gasolinefractionator of ethylene unit, which has the prominent characteristicsof anti-plugging, energy conservation and effectiveness enhancement.

In order to achieve the above purpose, the following technical proposalis adopted: a dual-flow-baffle compound gasoline fractionator ofethylene unit comprises a tower body as well as an orifice andinstruments thereof, the functional sections of the lower body are aquench oil circulation section comprising nozzle-type liquiddistributors and three-dimensional compound guide-type inlet initialdistributors, a medium oil circulation section comprising nozzle-typeliquid distributors and high-circulation oil collecting tanks, a dieseloil separation section, and a petroleum separation section comprisingnozzle-type liquid distributors, and the dual-flow-baffle compoundgasoline fractionator of ethylene unit is characterized in that: microbattles, which are arranged in parallel in the vertical direction atintervals, are arranged between the nozzle-type liquid distributors andthe three-dimensional compound guide-type inlet initial distributors ofthe quench oil circulation section, a vertex angle of the micro baffleranges from 90 to 139 degrees, symmetrical bevel edges at two sides ofthe vertex angle of the micro baffle are provided with symmetricalvertical hems, the length of the symmetrical bevel edges ranges from 80to 200 mm and the length of the vertical hems ranges from 10 to 40 mm;dual-flow trays, which are arranged in the vertical direction and havemeshes with the diameter ranging from Φ18 to 24 mm, are arranged betweenthe nozzle-type liquid distributors and the high-circulation oilcollecting tanks of the medium oil circulation section; dual-flow trays,which are arranged in the vertical direction and have meshes with thediameter ranging from Φ18 to 24 mm, are arranged on the diesel oilseparation section; and dual-flow trays, which are arranged in thevertical direction and have meshes with the diameter ranging from Φ13 to18 mm, are arranged below the nozzle-type liquid distributors of thepetroleum separation section.

The following technical measures may also be adopted in the invention:

The micro baffles arranged equidistantly have the free section rate of50±5% and the interlayer spacing ranging from 300 to 600 mm.

The quench oil circulation section is provided with 10 to 16 layers ofmicro baffles which are arranged in parallel in the vertical directionat intervals.

The micro baffles are supported by a space truss, the space truss isprovided with a foundation beam on which pillars are distributed atintervals, both layering and horizontal support of X-direction crossbeams and Y-direction cross beams are realized between the pillars andbetween the pillars on the periphery and the tower body, and theV-direction cross beams of all layers horizontally support the microbaffles

The percentage of open area of the dual-flow tray is from 15 to 30%.

8 to 10 layers of the dual-flow trays of the medium oil circulationsection are arranged in the vertical direction.

3 to 5 layers of the dual-flow trays of the diesel oil separationsection are arranged in the vertical direction.

7 to 10 layers of the dual-flow trays of the gasoline separation sectionare arranged in the vertical direction.

The dual-flow trays arranged in the vertical direction are supported bya one-bracket-supporting-multi-tray trussed beam, a middle parallelchord parallel to an upper parallel chord and a lower parallel chord isarranged between the upper parallel chord and the lower parallel chordwhich are both parallel to the trussed beam, and the side-by-side middleparallel chords are positioned symmetrically; the upper and lowerparallel chords and the middle parallel chords are composed ofsymmetrical section steels jointed side by side, rectangular chordplates are respectively fixedly clamped between the section steelsjointed side by side, a vertical rod and an oblique rod are fixedlywelded at two sides of the rectangular chord plate respectively, and theparallel upper and lower parallel chords and the middle parallel chordshorizontally support the dual-flow trays respectively.

The invention has the advantages that: the gasoline fractionator ofethylene unit is provided with the micro baffles at the quench oilcirculation section thereof and adopts medium-mesh ripple dual-flowtrays, having meshes with the diameter of Φ12 mm larger than that of themeshes of current relevant functional sections, for the medium oilcirculation section, a diesel oil separation section and a gasolineseparation section, thus the gasoline fractionator embodies thefollowing prominent effects:

1. The known self-cleaning function of the dual-flow tray issufficiently utilized and polymer plugging occurring frequently on thelocation of the dual-flow tray, the diesel oil separation section inparticular is overcome. The self-cleaning function of the dual-flow traymainly reflects that: (1) the tower tray fanned by the dual-flow traysis featured by gas-liquid counter flow, and the impact and stirring ofgas liquid enable solids in liquid to be uniformly mixed and to lift asthe liquid flow lifts, thereby avoiding the plugging resulted fromsediments. (2) the liquid on the tower tray formed by the dual-flowtrays moves only axially instead of gas-liquid cross flow, and is evenfree from residence area and dead space, thereby avoiding the pluggingresulted from the accumulation of solids. (3) the selected diameterranges of the meshes in the invention are respectively from Φ13 to 18 mm(medium-mesh) and from Φ18 to 24 mm (large-mesh), so the anti-pluggingcapability thereof is superior to the current common ripple dual-flowtrays with the diameter of Φ12 mm. (4) owing to the larger area of themeshes of the dual-flow tray in the invention, the solids in the liquidhardly result in bridging plugging of the meshes under the action ofairflow impact, so the anti-plugging capability thereof is superior tothe current common floating valve structure or fixed valve structure.

2. The pressure of the gasoline fractionator is further reduced,particularly, by about 50% compared with the pressure of floating valveor fixed valve tower tray, for example, the overall pressure drop of aΦ12600 gasoline fractionator introduced by one-million-ton ethylenedevice is about 20 KPa after the proposal of fixed valve dual-flow trayis adopted, while the overall pressure drop of the experimental tower ofthe same specification is less than 100 KPa. It can be estimatedaccording to the known common knowledge in this art, i.e. 150 Kw ofpower can be saved per hour by 1 KPa of the pressure drop and the yieldof ethylene increases by 0.1%, that the experimental tower saves 1500 Kwof power per hour and the yield of ethylene increases by 1%, i.e. 10000tons.

3. Since the spaces between the large-mesh dual-flow trays has thefunction of raining, the total mass transfer and heat transferefficiencies of the invention are superior to those of overflow-typetower tray. Practical tests have shown that, the temperature drop ofeach large-mesh dual-flow tray on the diesel oil separation section ofthe experimental tower of the invention is about 8 to 10° C., whichserves to signify the outstanding mass transfer and heat transferefficiencies of the gasoline fractionator of the invention.

According to the invention, the micro baffles for the quench oilcirculation section are products derived from the optimal combination ofcurrent large, middle baffles (compared with the micro baffles) andangle steel tower tray, and in addition to strong anti-pluggingcapability and lower pressure drop same as the large and middle baffle,the micro baffle also includes the direct heat transfer and indirectheat transfer efficiencies remarkably higher than those of the large andmiddle baffle. First of all, the number of the used micro baffles ateach layer is several times as much as that of the large and middlebaffles, so the times of direct gas-liquid contact of the micro bafflesis several times as much as that of the large and middle baffles;furthermore, the vertical hems, which are arranged at two sides of thevertex angle of the micro baffle, not only enhance the rigidness of themicro baffles, but also plays the role of flow guide.

In addition, the dual-flow trays of the invention are supported by aone-bracket-supporting-multi-tray trussed beam having the rigidness muchstronger than conventional trussed beam, therefore, not only the purposea multilayered tower trays are supported by one beam can be reached, thetechnical requirement that the levelness of large-diameter tower tray isnot more than 3 mm and the design requirement that the height of mainbeams of tower trays of all layers is smaller than 30% of plate spacingcan also be met. Proved by experiments, the trussed beam causes noinference to the liquid on the tower tray and no influence to uniformdistribution of gas, and is favorable for the enhancement of plateefficiency. Also, proved by experiments, the trussed beam has quitestrong impact vibration resistance. The trussed beam can obviously lowerthe entire cost of tower in contrast to the current multilayered towertray structure.

The micro baffles of the invention are supported by a space truss,therefore, the purpose of supporting a plurality or layers of the microbaffles can be reached, moreover, the gasoline fractionator has theprominent advantage of strong resistance to the impact of high-speedvariable gas load, can effectively avoid resonant vibration generated bythe impact of high-speed variable gas load so as to advantage long-termstable operation of tower, and simultaneously has the characteristics ofsmall manufacturing and installation difficulty and low cost.

In conclusion, the gasoline fractionator of the invention can thetechnical index of long-term stable operation dramatically and achievesenergy saving and efficiency improvement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structural section of theembodiment of the gasoline fractionator.

FIG. 2 is a schematic diagram of the cross section of the micro baffle.

FIG. 3 is an “A”-direction view of the FIG. 2.

FIG. 4 is a schematic diagram of the arrangement state of the microbaffles.

FIG. 5 is a schematic diagram of the local structure of the space truss.

FIG. 6 is an “A”-direction view of the FIG. 5.

FIG. 7 is a schematic diagram of the local section of the trussed beamin FIG. 1.

FIG. 8 is an enlarged view of the “A-A” section of FIG. 7.

The numbers in the figures are as below; 1 tower body, 2 pedestal, 3foundation beam, 4 space truss, 4-1 pedestal, 4-2 space truss foundationbeam, 4-3 pillar, 4-4 support base, 4-5 X-direction cross beam, 4-6Y-direction cross beam, 5 micro baffle, 6 nozzle-type liquiddistributor, 7 high-circulation oil collecting tank, 8 trussed beam, 8-1pedestal, 8-2 lower parallel chord, 8-3 rectangular chord plate, 8-4intermediate rectangular chord plate, 8-5 upper parallel chord, 8-6intermediate parallel chord, 8-7 oblique rod, 8-8 vertical rod, 8-9spacing rod, 8-10 connecting plate, 9 dual-flow tray and 10three-dimensional compound guide-type inlet initial distributor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further description is made below to the invention with reference to theembodiments and the drawings thereof.

Shown as FIG. 1, the gasoline fractionator of ethylene unit comprises atower body I as well as an orifice and instruments thereof (not shown),the functional sections of the tower body sequentially are a quench oilcirculation section A, a medium oil circulation section 8, a diesel oilseparation section C and a petroleum separation section D in anascending direction.

10 to 16 layers of micro baffles 5 are arranged between nozzle-typeliquid distributors 6 and three-dimensional compound guide-type inletinitial distributors 10 of the quench oil circulation section A, and inthe embodiment shown as FIG. 1, 15 layers of the micro baffles 5 arearranged and supported by a space truss 4, and structural description ismade below to the micro baffles 5 and the space truss 4 respectively.

Shown as FIG. 2, 3, a vertex angle α of the micro baffle 5 of the quenchoil circulation section A ranges from 90 to 130 degrees, symmetricalvertical hems 5-1 are arranged at the tail ends of symmetrical beveledges at two sides of the vertex angle, and the length T1 of thesymmetrical bevel edges ranges from 80 to 200 mm and the height T2 ofthe vertical hems 5-1 ranges from 10 to 40 mm.

Shown as FIG. 4, the micro baffles 5 in use are equidistantly arrangedin parallel in the vertical direction and is supported on a support beamof the space truss 4, and the micro baffles arranged equidistantly havethe free section rate of 50±5% and the interlayer spacing T3 rangingfrom 300 to 600 mm.

The space truss supporting the micro baffles in the embodiment 1 shownas FIG. 1 is structurally shown as FIGS. 5 and 6, the space truss isprovided with space truss foundation beams 4-2 supported by pedestals4-1, and the space truss foundation beam may be fence beam, are bridgebeam or grille beam in the prior art. Pillars 4-3 formed by square tubesare distributed at intervals on the surface of the space trussfoundation beam, both layering and horizontal support of X-directioncross beams 4-5 and Y-direction cross beams 4-6 are realized between thepillars and between the pillars on the periphery and the tower body 1,and two ends of the X-direction cross beams 4-5 and the Y-directioncross beams are fixedly connected with the corresponding pillars orsupport bases arranged in the tower body 1.

The Y-direction cross beams of the space truss shown as FIGS. 5 and 6horizontally support 8 or 7 layers of the micro baffles 5.

8 to 10 layers of dual-flow trays, which are arranged in the verticaldirection and have meshes with the diameter ranging from Φ18 to 24 mm,are arranged between the nozzle-type liquid distributors 6 and thehigh-circulation oil collecting tanks 7 of the medium oil circulationsection B, and 8 layers of the dual-flow trays, which have meshes withthe diameter of Φ22 mm are arranged in the embodiment shown as Figure I.

The dual-flow tray 9 in the embodiment shown as Figure I is supported bya one-bracket-supporting-four-tray trussed beam 8, structurally shown asFIGS. 7 and 8.

In FIGS. 7 and 8, the trussed beam 8 comprises side-by-side upperparallel chords 8-5, side-by-side lower parallel chords 8-2 (only twocolumns are shown in the figures), vertical rods 8-8 and oblique rods8-7, spacing rods 8-9 which are respectively arranged between theside-by-side upper parallel chords and between the lower parallel chordsas well as which connect the upper parallel chords with the lowerparallel chords and define the spacing, and connecting plates 8-10 whichare respectively used for the bodies of the upper and lower parallelchords.

The trussed beam of the invention is respectively provided with twointermediate parallel chords 8-6, parallel to the upper and lowerparallel chords, between the side-by-side upper and lower parallelchords, and the side-by-side intermediate parallel chords of the trussedbeam are symmetrically positioned.

In FIGS. 7 and 8, the upper parallel chord 8-5 and the lower parallelchord 8-2 are composed of symmetrical channel steels jointed side byside, and a rectangular chord plate 8-3 is clamped between thesymmetrical channel steels by means of welding-type fixation. Theintermediate parallel chord 8-6 is composed of symmetrical angle steelsjointed side by side, and an intermediate rectangular chord plate 8-4 isclamped between the symmetrical angle steels by means of welding-typefixation. In addition, the intermediate parallel chords 8-6 are alsoprovided with the connecting plates 10 for the connection with thebodies.

The side-by-side upper and lower parallel chords and the middle parallelchords of the trussed beam can horizontally support 4 layers of thedual-flow trays, therefore, two sets of the trussed beam are arranged inthe embodiment shown as FIG. 1 in order to support 8 layers of thedual-flow trays.

The bottom end of the one-bracket-supporting-four-tray trussed beamshown as FIGS. 7 and 8 is respectively provided with pedestals 8-1(omitted in FIG. 1). The diesel oil separation section C of theinvention is provided with 3 to 5 layers of the dual-flow trays, whichare arranged in the vertical direction and have meshes with the diameterranging from Φ13 to 24 mm, and in the embodiment shown as FIG. 1, 4layers of the dual-flow trays 9, which are arranged in the verticaldirection and have meshes with the diameter of Φ24 mm, are arranged. Thedual-flow trays 9 are supported by a one-bracket-supporting-four-traytrussed beam 8.

The dual-flow trays, which are arranged in the vertical direction andhave meshes with the diameter ranging from Φ13 to 18 mm, are arrangedbelow the nozzle-type liquid distributors 6 of the petroleum separationsection D of the invention, and in the embodiment shown as FIG. 11, 8layers of the dual-flow trays 9, which are arranged in the verticaldirection and have meshes with the diameter of Φ14 mm, are arranged. Thedual-flow trays 9 are supported by two sets of theone-bracket-supporting-four-tray trussed beam 8.

In the embodiment shown as FIG. 1, the percentages of open area of themedium oil circulation section B, the diesel oil separation section Cand the petroleum separation section D respectively are 20%, 18% and18%.

1. A dual-flow-baffle compound gasoline fractionator of ethylene unit,comprising a tower body as well as an orifice and instruments thereof,the functional sections of the tower body being a quench oil circulationsection comprising nozzle-type liquid distributors and three-dimensionalcompound guide-type inlet initial distributors, a medium oil circulationsection comprising nozzle-type liquid distributors and high-circulationoil collecting tanks, a diesel oil separation section, and a petroleumseparation section comprising nozzle-type liquid distributors,characterized in that: micro baffles, which are arranged in parallel inthe vertical direction at intervals, are arranged between thenozzle-type liquid distributors and the three-dimensional compoundguide-type inlet initial distributors of the quench oil circulationsection, a vertex angle of the micro baffle ranges from 90 to 139degrees, symmetrical bevel edges at two sides of the vertex angle of themicro baffle are provided with symmetrical vertical hems, the length ofthe symmetrical bevel edges ranges from 80 to 200 mm and the length ofthe vertical hems ranges from 10 to 40 mm; dual-flow trays, which arearranged in the vertical direction and have meshes with the diameterranging from Φ18 to 24 mm, are arranged between the nozzle-type liquiddistributors and the high-circulation oil collecting tanks of the mediumoil circulation section; dual-flow trays, which are arranged in thevertical direction and have meshes with the diameter ranging from Φ13 to24 mm, are arranged on the diesel oil separation section; and dual-flowtrays, which are arranged in the vertical direction and have meshes withthe diameter ranging from Φ13 to 18 mm, are arranged below thenozzle-type liquid distributors of the petroleum separation section. 2.The gasoline fractionator according to claim 1, characterized in that:the micro baffles arranged equidistantly have the free section rate of50±15% and the interlayer spacing ranging from 300 to 600 mm.
 3. Thegasoline fractionator according to claim 1, characterized in that: thequench oil circulation section is provided with 10 to 16 layers of microbaffles which are arranged in parallel in the vertical direction atintervals.
 4. The gasoline fractionator according to claim 1,characterized in that: the micro baffles are supported by a space truss,the space truss is provided with a foundation beam on which pillars aredistributed at intervals, both layering and horizontal support ofX-direction cross beams and Y-direction cross beams are realized betweenthe pillars and between the pillars on the periphery and the tower body,and the Y-direction cross beams of all layers horizontally support themicro baffles.
 5. The gasoline fractionator according to claim 1,characterized in that: the percentage of open area of the dual-flow trayis from 15 to 30%.
 6. The gasoline fractionator according to claim 1,characterized in that: 8 to 10 layers of the dual-flow trays of themedium oil circulation section are arranged in the vertical direction.7. The gasoline fractionator according to claim 1, characterized inthat: 3 to 5 layers of the dual-flow trays of the diesel oil separationsection are arranged in the vertical direction.
 8. The gasolinefractionator according to claim 1, characterized in that: 7 to 10 layersof the dual-flow trays of the gasoline separation section are arrangedin the vertical direction.
 9. The gasoline fractionator according toclaim 1, characterized in that; the dual-flow trays arranged in thevertical direction are supported by a one-bracket-supporting-multi-traytrussed beam, a middle parallel chord parallel to an upper parallelchord and a lower parallel chord is arranged between the upper parallelchord and the lower parallel chord which are both parallel to thetrussed beam, and the parallel middle parallel chords are positionedsymmetrically; the upper and lower parallel chords and the middleparallel chords are composed of symmetrical section steels jointed sideby side, rectangular chord plates are respectively fixedly clampedbetween the section steels jointed side by side, a vertical rod and anoblique rod are fixedly welded at two sides of the rectangular chordplate respectively, and the parallel upper and lower parallel chords andthe middle parallel chords horizontally support the dual-flow traysrespectively.